Hydraulic action devices with inertia insensitive snubbing circuit

ABSTRACT

A hydraulic action device such as a buffer, actuator, and the like, comprises means defining a working chamber from which hydraulic fluid is arranged to be displaced through one or more passages by a member such as a wing shaft vane, and the like, operative under substantial load variables, and a valve is referenced directly to the working chamber independently of and in control of at least one of the passages for effecting a substantially uniform rate of deceleration of the member irrespective of load, force or inertia. Anticavitation valve means and speed control valve means may be provided.

United States Patent 1 3,631,761

[72] Inventor Rollin Douglas Rumsey [56] References Cited 21 A l N ggggg UNITED STATES PATENTS E fig $29,196,; 2,464,283 3/1949 Adams 91/421Patented Jan. 4 1972 3,323,422 6/1967 Freese 91/409 Assignee HoudaiueIndustries, ha 3,470,792 10/1969 Darl ng... 91/408 Buffalo, 3,054,3849/1962 Darling 9 H26 original application Sept. 18,1967, sen 3,103,2819/1963 Rumsey et al. 91/26 No. 668,716 now Patent 3,419,114 3,303,7462/1967 Schmoeger 91/26 dated Dec. 31, 1968, Continuation of PrimaryExaminer-Paul E. Maslousky applica n ,Jan- 27, AttorneyHill, Sherman,Meroni, Gross & Simpson 1966, now abandoned. Divided and thisapplication Aug. 29, 1968, Ser. No.

756,228 ABSTRACT: A hydraulic action device such as a buffer, ac-

tuator, and the like, comprises means defining a working chamber fromwhich hydraulic fluid is arranged to be dis- HYDRAULIC ACTION DEVICESWIT NERTIA placed through one or more passages by a member such as aINSENSITIVE N BB CIRCUIT wing shaft vane, and the like, operative undersubstantial load l7Claim ,2DraWing ig variables, and a valve isreferenced directly to the working [52] US. Cl 91/408, chamberindependently of and in Control of at least one of the 91/420 91/42191/437 passages for effecting a substantially uniform rate of decelera-51 lm. Cl ..Fl5b 15/22, of the member ifrfislecfi"e bad, fme inertiaFlsb 11/08 Flsb 13/042 ticavitation valve means and speed control valvemeans may 50 Field of Search 91/405, 26, be P PATENIED JAN 4 m2 SHEET 2OF 2 1 EN'IUR.

HYDRAULIC ACTION DEVICES WITH INERTIA INSENSITIVE SNUBBING CIRCUIT Thepresent application is a division of my application, Ser. No. 668,716,filed Sept. 18, 1967, now US. Pat. No. 3,419,114, dated Dec. 31, 1968which is a streamlined continuation of my application, Ser. No. 523,426,filed Jan. 27, 1966, now abandoned.

This invention relates to improvements in hydraulic action devices onthe order of shock absorbers, buffers, rotary actuators, and the like,and more particularly concerns inertia insensitive snubbing circuitmeans especially useful with such devices.

In the operation of hydraulic action devices of the type indicated, aserious problem has existed in respect to stopping variable inertialoads. Generally a compromise setting or adjustment has been establishedin the associated hydraulic cir cuitry to accommodate the mean inertiaforce, or at least the force predominantly encountered in the use of thedevice. Hence, in substantially higher inertias there is a strongtendency for the hydraulic stopping means to bottom out, whereas, if theinertia load is substantially lighter excessively high decelerationforces are encountered.

For example, difiiculties are encountered in hydraulic actuators of thekind used on earth moving equipment such as the swing actuators onbackhoes, If the hydraulic control circuitry is designed to stop thebackhoe under an average inertia load condition, should the operator ofthe equipment inexpertly come into the stops with the boom fullyextended and the bucket fully loaded, the hydraulic actuator generallywill not stop it and the boom will ram into the solid stops withdestructive force. On the other hand, if snubbing is made strong enoughin the system to stop the boom under the worst condition, then when theboom is in close, or lightly loaded, the speed of operation of thebackhoe will be severely limited near the ends of travel because of thehigh braking force exerted, resulting in excessively slow operation.

Accordingly, it is an important object of the present invention toprovide in hydraulic action devices a new and improved inertiainsensitive snubbing circuit in which snubbing will be in proportion tothe inertia forces exerted in order always to bring the load to rest atthe same rate.

Another object of the invention is to provide a new and improvedsnubbing circuit for hydraulic action devices of the character indicatedin which the load will be brought to rest from a predetermined speed ata constant G force irrespective of the amount of inertia in the load,such that if the inertia is high the snubbing pressure will be high andif the inertia is low the snubbing pressure will be low.

A further object of the invention is to provide new and improvedbufi'ing means affording the maximum efficiency at all times and capableof protecting the associated equipment from abuse by abnormal inertiaload conditions, operator variation or inconsistency, and the like.

Another object of the invention is to provide new and improved inertiainsensitive snubbing control means comprising novel control valvestructure and pressure referencing means therefor.

Other objects, features and advantages of the present invention will bereadily apparent from the following detailed description of certainpreferred embodiments thereof taken in conjunction with the accompanyingdrawings, in which:

FIG, 1 is a schematic illustration ofa rotary hydraulic buffer oractuator including a snubbing circuit arrangement embodying features ofthe invention; and

FIG. 2 is a schematic illustration of a rotary buffer or actuator with amodification of the novel inertia insensitive snubbing circuit featuresof the invention.

Application of the principles of the present invention to a rotary vanetype of hydraulic actuator 35 is represented in FIG. 1. In such anactuator a tubular housing body 37 is closed at its opposite ends bymeans of end closure members 38 and defines a cylindrical workingchamber 39 in which is fixedly mounted at least one abutment 40 havingan inwardly project- 48 is provided for selectively determiningconnection of thepressure and return lines 45 and 47 with respectivehydraulic fluid displacement control circuit passages 49 connected atone end with the control valve and at their opposite ends with therespective working subchambers through an orifice 50 in each instanceopening through one of the end closures 38 adjacent to the abutment 40and in that portion of the subchamber toward which the vane 43 is drivenin each respective direction of oscillation in operation. In addition,each of the orifices 50 is so located and shaped that as the vane 43approaches its respective limit at the abutment 40 the displacementorifice is progressively closed off for rapid deceleration of the wingshaft. A generally teardrop shape of each of the orifices 50 with itswidest portion at the end toward which the vane approaches is desirablefor progressive deceleration cutoff.

To assure constant snubbing deceleration irrespective of inertia, areciprocable plunger valve 51 is mounted in a bore 52 which intersectsthe passage 49. Normally the valve 51 is biased toward one end of thebore 52 by means of a coiled compression spring 53 so as to leave thepassage 49 open. At its end opposite the biasing spring 53, the valve 51is referenced to the portion of the associated working subchamber towardwhich the actuator vane 43 is liable to generate pressure in response toexternal force through the shaft 42. Reference is effected by a pilotpressure connecting passage duct 54 having at its subchamber end anorifice 55 located beyond the orifice 50, considered with respect to theworking stroke approach of the vane member 43, and adjacent to theabutment 40 clear of the vane 43 and its adjacent terminal position, asindicated in dash outline in FIG. 1. Through this arrangement, thesnubbing valve 51 responds to vane generated pressure in the associatedworking subchamber for automatically controlling an orifice or port 57affording communication of the passage 49 with the bore 52. For startingthe wing shaft in a reverse stroke, even though the adjacentdeceleration metering orifice 50 is closed off by the vane 43, each ofthe valves 51 is provided with an orifice 58 therethrough controlled bya ball check valve 59 at its end referenced to the subchamber throughthe passage 54, whereby to enable the wing shaft vane 43 to be movedrapidly away from the abutment 40, by pressure fluid introduced throughthe passage 49.

A further refinement of the inertia insensitive snubbing circuit isdepicted in FIG. 2, in respect to a rotary vane hydraulic actuator 60including a housing 61 defining a cylindrical working chamber 62 closedat the opposite ends by respective end closures 63 and having mountedtherein at least one fixed abutment 64 with an inner edge having a seal65 and slidably cooperating with an oscillatable wing shaft 67 having avane 68 with an edge provided with a seal 69 slidably engaging the wallsdefining the working chamber 62 and cooperating with the abutment 64 todivide the working chamber into subchambers. A hydraulic pressure supplyline 70 and a return line 71 are connected through a conventionalfour-way plunger control valve 72 with the respective subchambers of theactuator through inertia insensitive snubbing circuit passages 73, eachof which communicates with its subchamber through a respective port 74in one of the end members 63 and having a pattern of communicationorifices 75 which are adapted to be progressive closed as the vane 68approaches the terminal limit of its stroke toward the abutment 64 inorder to decelerate the wing shaft rapidly. Each of the circuit passages73 has speed control valve means 77 including an adjustable orifice orthrottle valve portion 770 and a one-way check valve portion 77b. Forenabling rapid movement of the actuator vane 68 away from the abutment64 even though the port 74 is fully covered, a respective orifice 78located in the comer of the subchamber adjacent the abutment 64 clear ofthe vane in its terminal position affords communication with a duct 79which is in communication through a one-way check valve 80 with thepassage 73. Anticavitation or overrun preventing means are providedcomprising a pair of crossover relief valves 81 which interconnect thetwo subchambers in order to prevent excessive pressure being developedin the actuator in the event the control valve 72 is abruptly centeredwhen the actuator is moving at maximum speed. These valves 81 areconnected across the ducts 79 and are biased in respective opposition tothe direction of pressure movement of the hydraulic fluid from therespective ducts and responsive to predetermined pressure to throttlepassage of hydraulic fluid through these valves respectively. Aspressure builds up in the respective subchambers incident to closing ofthe orifices 75 in the terminal portion of the vane stroke, aplunger-type throttle valve 82 in a bore 83 intersecting the passage 73through which hydraulic fluid from the pressure line 70 is beingdelivered is pressurized through a branch 84 from the duct 79. Thiscauses the pressurized valve 82 to move in opposition to a normallybiasing coiled compression spring 85 to throttle a port 87 in thepassage 73 which is in communication with the pressure line 70.

To provide constant snubbing deceleration irrespective of inertia, aplunger valve 88 mounted in the opposite end portion of the bore 83, andnormally biased by the spring 85 to leave a port 89 in the associatedpassage 73 open, is referenced directly to its associated subchamberthrough a branch 90 leading from the duct 79 in its circuit. Since thebiasing spring 85 bottoms under biasing compression oppositely againstthe companion inlet cutoff valve 82 and snubbing valve 88, these valvesserve automatically to load the spring toward the opposite valve underrespective pressure fluid thrust, thus attaining automatic biasingcontrol in operation. Otherwise, functioning of the snubbing valve 88 issubstantially the same as described for the snubbing valve 51 of FIG. 1.

ln all forms of the invention, an important feature resides in affordingmaximum efficiency in operation of the hydraulic action device,protecting the equipment from the inevitable abuses, extraordinaryinertia loads either above or below the normal range, variations orinconsistencies in operators handling of the equipment, etc.

It will be understood that modifications and variations may be effectedwithout departing from the scope of the novel concepts or the presentinvention.

I claim as my invention:

1. A hydraulic reaction device comprising a rotary vane actuator having:

a housing providing a cylindrical working chamber having fixed abutmentmeans therein;

a rotary wing shaft joumaled in the housing and having vane meanscooperating with said cylinder and said abutment means to subdivide theworking chamber into subchambers;

means providing respective hydraulic fluid displacement control circuitpassages having connections with the respective subchambers for fluiddriven from said subchambers by pressure generated in working strokes ofsaid wingshaft and each including orifice means adjacent to the abutmentmeans and located to be progressively closed off in the terminal portionof the movement of the vane means toward the abutment means,

each of said passages having a snubber valve; and

a respective pilot pressure duct connected with each of said subchambersadjacent to the abutment means and beyond the range of said vane meansand referencing the respective subchamber for pressure fluid thrust todrive the snubber valve referenced to the pressure, thereby to drive thevalve into throttling snubbing relation to its passage.

2. A device according to claim I, having means for delivering operatinghydraulic fluid to said subchambers through said passages, said snubbervalves comprising respective plungers each including a check valvedpassage therethrough for starting hydraulic pressure fluid flow throughits associated duct to effect reversal of the wing shaft when the vanemeans are in closing relation to said orifice means.

3. A device according to claim I, having means for delivering operatinghydraulic fluid to said subchambers through said passages, said passagesand said ducts having respective check valved connections for bypassingstarting hydraulic fluid from said passage to the duct in each instancefor reversal of the wing shaft from the respective terminal positions ofthe vane means.

4. A device according to claim 1, including a respective throttle valveadditionally in control of each of said passages, and a respectiveoperating pressure fluid thrust reference connection provided betweeneach of said throttle valves and the duct leading from the other of saidsubchambers than that subchamber with which the passage controlled bythe valve is connected.

5. A device according to claim 4, said snubber valve and said throttlevalve in each passage comprising respective plungers having a commonbiasing spring thrusting at its opposite ends respectively thereagainstand normally biasing the plungers into clearance relation to thepassage.

6. A hydraulic action device comprising: means defining a workingchamber; a relatively reciprocably movable member in said chamberadapted to be driven by hydraulic fluid pressure in respective oppositeworking stroke and also adapted to generate fluid pressure in responseto external forces; fluid displacement passage means comprising, incommunication with said chamber at each opposite side of said member, arespective normal flow passage connectable selectively through controlmeans with a hydraulic fluid pressure source and an exhaust, and a pilotpressure passage connected with a control valve in said normal flowpassage; first orifice means at the chamber end of each of said normalflow passages located to be progressively closed off by said member in aworking stroke theretoward; and

second orifice means at the chamber end of said pilot passages locatedbeyond said first orifice means, considered with respect to the workingstroke approach of said member theretoward, and through which pressureis referenced to said valve to control the pressure drop across saidfirst orifice to efiect uniform deceleration snubbing of said movablemember irrespective of said external forces.

7. A device according to claim 6, having crossover relief valvesinterconnecting said pilot pressure passages.

8. A device according to claim 6, having check valve means permittingflow from said normal flow passage to the pilot pressure passageconnected therewith.

9. A device according to claim 6, having in at least one of saiddisplacement passage means cutoff valve means referenced to the portionof the working chamber to which the other of said displacement passagemeans are connected and operative to throttle said one passage meanswhile serving to deliver hydraulic fluid from said source to saidworking chamber if the pressure in that portion of the working chamberto which said other passage means are connected exceeds the deliveredfluid pressure.

10. A device according to claim 9, in which said control valve and saidcutoff valve means comprise respective valve pistons in a valve chamberwhich intersects the respective main flow passage, and common biasingmeans which holds said plungers in respective inactive positions.

1 l. A hydraulic reaction device comprising:

means defining a working chamber having hydraulic fluid therein;

means relatively movably operative in substantial working strokes inrespectively opposite directions in said working chamber and generatinghydraulic pressure in respective opposite portions of the chamber;

means providing respective hydraulic fluid displacement control circuitpassages connected to said portions of the chamber for fluid driven fromsaid portions of the chamber by the pressure generated in said workingstrokes by said movable means and each including orifice means theeffective flow area of which is progressively closed off by said movablemeans at least during the last part of the respective working stroke toeffect snubbing deceleration of said relative movement and resulting insubstantial increase in said hydraulic pressure;

respective means including ducts directly referenced to said portions ofthe chamber independently of said passages and responsive to saidincrease in pressure to throttle and control said respective passagesfor effecting a substantially uniform rate of deceleration of saidmovable means irrespective of load, force or inertia; and

anticavitation means connected between said ducts.

12. A hydraulic reaction device comprising:

means defining a working chamber having hydraulic fluid therein;

means relatively movably operative in substantial working strokes inrespectively opposite directions in said working chamber and generatinghydraulic pressure in respective opposite portions of the chamber;

means providing respective hydraulic fluid displacement control circuitpassages connected to said portions of the chamber for fluid driven fromsaid portions of the chamber by the pressure generated in said workingstrokes by said movable means and each including orifice means theeffective flow area of which is progressively closed off by said movablemeans at least during the last part of the respective working stroke toeffect snubbing deceleration of said relative movement and resulting insubstantial increase in said hydraulic pressure;

respective means directly referenced to said portions of the chamberindependently of said passages and responsive to said increase inpressure to throttle and control said respective passages for effectinga substantially uniform rate of deceleration of said movable meansirrespective of load, force or inertia; and

speed control valve means in said hydraulic fluid displacement controlcircuit passages in addition to said respective means directlyreferenced to said portions of the chamber.

13. A hydraulic reaction device comprising a rotary vane actuatorhaving:

a housing defining a cylindrical working chamber;

fixed abutment means in said working chamber;

a rotary wing shaft joumaled in the housing and having vane meanscooperating with said cylinder and said abutment means in a substantialworking stroke under likelihood of substantial load variables and insaid stroke generating hydraulic pressure in at least a portion of thechamber;

means providing a hydraulic fluid displacement control circuit passageconnected to said portion of the chamber for fluid driven from saidportion of the chamber by the pressure generated in said working strokeby said vane means and including orifice means the effective flow areaof which is progressively closed off by said vane means at least duringthe last part of said working stroke to effect snubbing deceleration ofsaid relative movement and resulting in substantial increase in saidhydraulic pressure, said orifice means being closed off to attainmaximum hydraulic pressure at the terminus of said working stroke; and

means spaced a substantial distance from the terminus of working strokeof said vane means and directly referenced to said portion of thechamber independently of said passage and responsive to said increase inpressure to throttle and control said passage for effecting asubstantially uniform rate of deceleration of said vane meansirrespective of load, force or inertia.

14. A hydraulic reaction device comprising:

means defining a working chamber having hydraulic fluid therein;

means relatively movably operative through a substantial working strokein said working chamber under likelihood of substantial load variablesand in said stroke generating hydraulic pressure in at least a portionof the chamber;

means providing a hydraulic fluid displacement control circuit passageconnected to said portion of the chamber for fluid driven from saidportion of the chamber by the pres sure generated in said working strokeby said movable means and including orifice means the effective flowarea of which is progressively closed off by said movable means at leastduring the last part of said working stroke to effect snubbingdeceleration of said relative movement and resulting in substantialincrease in said hydraulic pressure, said orifice means being completelyclosed off to attain maximum hydraulic pressure at the terminus of saidworking stroke;

means spaced a substantial distance from the terminus of working strokeof said movable means and directly referenced to said portion of thechamber independently of said passage and responsive to said increase inpressure to throttle and control said passage for effecting asubstantially uniform rate of deceleration of said movable meansirrespective of load, force or inertia; and

speed control means in said fluid displacement control circuit passagein addition to said means to throttle and control said passage.

15. A hydraulic reaction device comprising:

means defining a working chamber having hydraulic fluid therein;

means relatively movably operative in substantial working strokes inrespectively opposite directions in said working chamber and generatinghydraulic pressure in respective opposite portions of the chamber;

means providing respective hydraulic fluid displacement control pressuregenerated in said working strokes by said movable means and eachincluding orifice means the effective flow area of which isprogressively closed off by said movable means at least during the lastpart of the respective working stroke to effect snubbing deceleration ofsaid relative movement and resulting in substantial increase in saidhydraulic pressure; and

respective means including ducts directly referenced to said portions ofthe chamber independently of said passages and responsive to saidincrease in pressure in either of said passages to throttle and controlthe other of said passages.

16. A hydraulic reaction device comprising:

means defining a working chamber having hydraulic fluid therein;

means relatively movably operative in substantial working strokes inrespectively opposite directions in said working chamber and generatinghydraulic pressure in respective portions of the chamber;

means providing respective hydraulic fluid displacement control circuitsconnected to said portions of the chamber for fluid displaced withrespect to said portions of the chamber and each circuit includingorifice means connecting it with its respective portion of the chamberand the effective flow area of which orifice means is progressivelyclosed off by said movable means at least during the last part of therespective working stroke to effect snubbing deceleration of therelative movement of the relatively movable means and resulting insubstantial increase in hydraulic pressure in the respective portion ofthe working chamber; and

respective means referenced to said portions of the chamberindependently of said orifice means and responsive to said increase inhydraulic pressure in either of said chamber portions to control thecontrol circuit connected to the other of said portions of the chamber.

17. Pressure governing apparatus for a hydraulic actuator experiencingheavy inertia loads, which actuator includes a housing defining aworking chamber having a differential pressure movable barriertraversing said chamber and dividing it into two variable volumechambers each of which alternately acts as an intake chamber having aport therein connected by an intake line to a source of hydraulicpressure, while the other acts as a discharge chamber having a porttherein connected to a discharge or exhaust line, and which actuatoralso includes variable orificing means cooperating with the dischargeport for cushioning the end of the stroke of the movable barrier, thepressure governing apparatus comprismg:

shutoff valve means positioned in said intake line, normally springbiased to an open position; valve operator means responsive to apredetermined pressure in the discharge chamber which is greater thanthe operating pressure in said chamber operatively connected to theshutoff valve means, which latter, upon actuation overrides the valvespring, closes the valve and maintains it closed so long as saidpressure exists, and thereby blocks flow from the pressure source intothe inlet chamber, which effectively reduces the maximum pressureexperienced in the discharge chamber during any portion of the stroke;passage means connecting the discharge chamber with the intake chamber;and a high-pressure relief valve positioned in said passage meanspermitting flow only from the discharge chamber to the intake chamber toprevent excessive pressure development in the actuator.

* i i t t

1. A hydraulic reaction device comprising a rotary vane actuator having:a housing providing a cylindrical working chamber having fixed abutmentmeans therein; a rotary wing shaft journaled in the housing and havingvane means cooperating with said cylinder and said abutment means tosubdivide the working chamber into subchambers; means providingrespective hydraulic fluid displacement control circuit passages havingconnections with the respective subchambers for fluid driven from saidsubchambers by pressure generated in working strokes of said wing shaftand each including orifice means adjacent to the abutment means andlocated to be progressively closed off in the terminal portion of themovement of the vane means toward the abutment means; each of saidpassages having a snubber valve; and a respective pilot pressure ductconnected with each of said subchambers adjacent to the abutment meansand beyond the range of said vane means and referencing the respectivesubchamber for pressure fluid thrust to drive the snubber valvereferenced to the pressure, thereby to drive the valve into throttlingsnubbing relation to its passage.
 2. A device according to claim 1,having means for delivering operating hydraulic fluid to saidsubchambers through said passages, said snubber valves comprisingrespective plungers each including a check valved passage therethroughfor starting hydraulic pressure fluid flow through its associated ductto effect reversal of the wing shaft when the vane means are in closingrelation to said orifice means.
 3. A device according to claim 1, havingmeans for delivering operating hydraulic fluid to said subchambersthrough said passages, said passages and said ducts having respectivecheck valved connections for bypassing starting hydraulic fluid fromsaid passage to the duct in each instance for reversal of the wing shaftfrom the respective terminal positions of the vane means.
 4. A deviceaccording to claim 1, including a respective throttle valve additionallyin control of each of said passages, and a respective operating pressurefluid thrust reference connection provided between each of said throttlevalves and the duct leading from the other of said subchambers than thatsubchamber with which the passage controlled by the valve is connected.5. A device according to claim 4, said snubber valve and said throttlevalve in each passage comprising respective plungers having a commonbiasing spring thrusting at its opposite ends respectively thereagainstand normally biasing the plungers into clearance relation to thepassage.
 6. A hydraulic action device comprising: means defining aworking chamber; a relatively reciprocably movable member in saidchamber adapted to be driven by hydraulic fluid pressure in respectiveopposite working stroke and also adapted to generate fluid pressure inresponse to external forces; fluid displacement passage meanscomprising, in communication with said chamber at each opposite side ofsaid member, a respective normal flow passage connectable selectivelythrough control means with a hydraulic fluid pressure source and anexhaust, and a pilot pressure passage connected with a control valve insaid normal flow passage; first orifice means at the chamber end of eachof said normal flOw passages located to be progressively closed off bysaid member in a working stroke theretoward; and second orifice means atthe chamber end of said pilot passages located beyond said first orificemeans, considered with respect to the working stroke approach of saidmember theretoward, and through which pressure is referenced to saidvalve to control the pressure drop across said first orifice to effectuniform deceleration snubbing of said movable member irrespective ofsaid external forces.
 7. A device according to claim 6, having crossoverrelief valves interconnecting said pilot pressure passages.
 8. A deviceaccording to claim 6, having check valve means permitting flow from saidnormal flow passage to the pilot pressure passage connected therewith.9. A device according to claim 6, having in at least one of saiddisplacement passage means cutoff valve means referenced to the portionof the working chamber to which the other of said displacement passagemeans are connected and operative to throttle said one passage meanswhile serving to deliver hydraulic fluid from said source to saidworking chamber if the pressure in that portion of the working chamberto which said other passage means are connected exceeds the deliveredfluid pressure.
 10. A device according to claim 9, in which said controlvalve and said cutoff valve means comprise respective valve pistons in avalve chamber which intersects the respective main flow passage, andcommon biasing means which holds said plungers in respective inactivepositions.
 11. A hydraulic reaction device comprising: means defining aworking chamber having hydraulic fluid therein; means relatively movablyoperative in substantial working strokes in respectively oppositedirections in said working chamber and generating hydraulic pressure inrespective opposite portions of the chamber; means providing respectivehydraulic fluid displacement control circuit passages connected to saidportions of the chamber for fluid driven from said portions of thechamber by the pressure generated in said working strokes by saidmovable means and each including orifice means the effective flow areaof which is progressively closed off by said movable means at leastduring the last part of the respective working stroke to effect snubbingdeceleration of said relative movement and resulting in substantialincrease in said hydraulic pressure; respective means including ductsdirectly referenced to said portions of the chamber independently ofsaid passages and responsive to said increase in pressure to throttleand control said respective passages for effecting a substantiallyuniform rate of deceleration of said movable means irrespective of load,force or inertia; and anticavitation means connected between said ducts.12. A hydraulic reaction device comprising: means defining a workingchamber having hydraulic fluid therein; means relatively movablyoperative in substantial working strokes in respectively oppositedirections in said working chamber and generating hydraulic pressure inrespective opposite portions of the chamber; means providing respectivehydraulic fluid displacement control circuit passages connected to saidportions of the chamber for fluid driven from said portions of thechamber by the pressure generated in said working strokes by saidmovable means and each including orifice means the effective flow areaof which is progressively closed off by said movable means at leastduring the last part of the respective working stroke to effect snubbingdeceleration of said relative movement and resulting in substantialincrease in said hydraulic pressure; respective means directlyreferenced to said portions of the chamber independently of saidpassages and responsive to said increase in pressure to throttle andcontrol said respective passages for effecting a substantially uniformrate of deceleration of said movable means irrespective of load, forceor inertia; anD speed control valve means in said hydraulic fluiddisplacement control circuit passages in addition to said respectivemeans directly referenced to said portions of the chamber.
 13. Ahydraulic reaction device comprising a rotary vane actuator having: ahousing defining a cylindrical working chamber; fixed abutment means insaid working chamber; a rotary wing shaft journaled in the housing andhaving vane means cooperating with said cylinder and said abutment meansin a substantial working stroke under likelihood of substantial loadvariables and in said stroke generating hydraulic pressure in at least aportion of the chamber; means providing a hydraulic fluid displacementcontrol circuit passage connected to said portion of the chamber forfluid driven from said portion of the chamber by the pressure generatedin said working stroke by said vane means and including orifice meansthe effective flow area of which is progressively closed off by saidvane means at least during the last part of said working stroke toeffect snubbing deceleration of said relative movement and resulting insubstantial increase in said hydraulic pressure, said orifice meansbeing closed off to attain maximum hydraulic pressure at the terminus ofsaid working stroke; and means spaced a substantial distance from theterminus of working stroke of said vane means and directly referenced tosaid portion of the chamber independently of said passage and responsiveto said increase in pressure to throttle and control said passage foreffecting a substantially uniform rate of deceleration of said vanemeans irrespective of load, force or inertia.
 14. A hydraulic reactiondevice comprising: means defining a working chamber having hydraulicfluid therein; means relatively movably operative through a substantialworking stroke in said working chamber under likelihood of substantialload variables and in said stroke generating hydraulic pressure in atleast a portion of the chamber; means providing a hydraulic fluiddisplacement control circuit passage connected to said portion of thechamber for fluid driven from said portion of the chamber by thepressure generated in said working stroke by said movable means andincluding orifice means the effective flow area of which isprogressively closed off by said movable means at least during the lastpart of said working stroke to effect snubbing deceleration of saidrelative movement and resulting in substantial increase in saidhydraulic pressure, said orifice means being completely closed off toattain maximum hydraulic pressure at the terminus of said workingstroke; means spaced a substantial distance from the terminus of workingstroke of said movable means and directly referenced to said portion ofthe chamber independently of said passage and responsive to saidincrease in pressure to throttle and control said passage for effectinga substantially uniform rate of deceleration of said movable meansirrespective of load, force or inertia; and speed control means in saidfluid displacement control circuit passage in addition to said means tothrottle and control said passage.
 15. A hydraulic reaction devicecomprising: means defining a working chamber having hydraulic fluidtherein; means relatively movably operative in substantial workingstrokes in respectively opposite directions in said working chamber andgenerating hydraulic pressure in respective opposite portions of thechamber; means providing respective hydraulic fluid displacement controlpressure generated in said working strokes by said movable means andeach including orifice means the effective flow area of which isprogressively closed off by said movable means at least during the lastpart of the respective working stroke to effect snubbing deceleration ofsaid relative movement and resulting in substantial increase in saidhydraulic pressure; and respective means including ducts directlyreferenced to said poRtions of the chamber independently of saidpassages and responsive to said increase in pressure in either of saidpassages to throttle and control the other of said passages.
 16. Ahydraulic reaction device comprising: means defining a working chamberhaving hydraulic fluid therein; means relatively movably operative insubstantial working strokes in respectively opposite directions in saidworking chamber and generating hydraulic pressure in respective portionsof the chamber; means providing respective hydraulic fluid displacementcontrol circuits connected to said portions of the chamber for fluiddisplaced with respect to said portions of the chamber and each circuitincluding orifice means connecting it with its respective portion of thechamber and the effective flow area of which orifice means isprogressively closed off by said movable means at least during the lastpart of the respective working stroke to effect snubbing deceleration ofthe relative movement of the relatively movable means and resulting insubstantial increase in hydraulic pressure in the respective portion ofthe working chamber; and respective means referenced to said portions ofthe chamber independently of said orifice means and responsive to saidincrease in hydraulic pressure in either of said chamber portions tocontrol the control circuit connected to the other of said portions ofthe chamber.
 17. Pressure governing apparatus for a hydraulic actuatorexperiencing heavy inertia loads, which actuator includes a housingdefining a working chamber having a differential pressure movablebarrier traversing said chamber and dividing it into two variable volumechambers each of which alternately acts as an intake chamber having aport therein connected by an intake line to a source of hydraulicpressure, while the other acts as a discharge chamber having a porttherein connected to a discharge or exhaust line, and which actuatoralso includes variable orificing means cooperating with the dischargeport for cushioning the end of the stroke of the movable barrier, thepressure governing apparatus comprising: shutoff valve means positionedin said intake line, normally spring biased to an open position; valveoperator means responsive to a predetermined pressure in the dischargechamber which is greater than the operating pressure in said chamberoperatively connected to the shutoff valve means, which latter, uponactuation overrides the valve spring, closes the valve and maintains itclosed so long as said pressure exists, and thereby blocks flow from thepressure source into the inlet chamber, which effectively reduces themaximum pressure experienced in the discharge chamber during any portionof the stroke; passage means connecting the discharge chamber with theintake chamber; and a high-pressure relief valve positioned in saidpassage means permitting flow only from the discharge chamber to theintake chamber to prevent excessive pressure development in theactuator.